Metal fibers obtained by bundled drawing

Abstract

Metal fibers obtained by the bundled drawing of a composite bundle of metal wires embedded in a metal matrix followed by the electrolytic removal of the matrix so that the surface layers of the fibers contain only a negligible amount (≦0.2% at) of the matrix metal. Furthermore, a description is given of a process and an apparatus for the continuous electrolytic removal of the matrix material. Thereby, the composite bundle acts as an anode. Stainless steel fibers according to the invention have an average Cr/Cr+Fe+Ni content at their surface between 1% and 15%.

I claim: 
     
       1. A process for the manufacture of metal fibers by bundled drawing in which the metal matrix is removed by an electrolytic process and in which the embedded bundle acts as an anode characterized in that the embedded bundle (1) is continuously transported through successive electrolytic baths (2, 4) containing an electrolyte at a temperature of at least 20° C. without making mechanical contact with current carrying contact elements and in which cathodic transition cells (6) are present between these baths and in which the current runs through the bundle (1) between these paths and transition cells and in which at least part of the matrix material is deposited on cathodes (5) which are facing the bundle. 
     
     
       2. A process according to claim 1, in which the metal matrix consists of copper and the electrolyte contains H 2  SO 4  and CuSO 4 . 
     
     
       3. A process according to claim 1, in which the metal matrix consists of copper surrounded by a steel jacket and in which the steel layer is removed in H 2  SO 4  baths in a first series of cells (2) while the Cu is removed in H 2  SO 4  /CuSO 4  containing baths in a next series of cells (4). 
     
     
       4. A process according to claim 1, wherein the bundles are supported at the level or in the vicinity of the transition zones (10) where most of the current is conducted by the bundle (1). 
     
     
       5. A process according to claim 1, wherein the current supply for the electrolysis is regulated with a stabilized current and with current densities between 5 and 75 A/dm 2  of bundle surface. 
     
     
       6. A process according to claim 5 wherein the current is supplied by way of successive separated power supply circuits each of which serves one of the successive series of baths, and wherein a series of baths may contain one of more baths (2) resp. (4). 
     
     
       7. A process for the manufacture of metal fibers by bundled drawing in which the metal matrix is removed by an electrolytic process and in which the embedded bundle acts as an anode characterized in that the said bundle, stored in a layer on a liquid-pervious metallic support frame which is anodically polarized, is submerged in a H 2  SO 4  containing bath above room temperature and provided with circulating or stirring means for the electrolyte and faces at least one cathodically polarized metal electrode, and whereby the electrodes are connected to a voltage stabilized rectifier. 
     
     
       8. A process according to claim 7, wherein the applied voltage is less than 2,5 V and the current is less than 20 A per kg of composite to be treated.